In a photolithography process of manufacturing processes of a semiconductor device, a resist coating processing is performed to form a resist film on the surface of a semiconductor wafer (“wafer”). In general, a spin coating method is adopted as the coating processing. As illustrated in FIG. 9, the spin coating method is a method in which a resist liquid is supplied to a center portion of a wafer W from a nozzle 11 in a state where wafer W is fixed on a spin chuck 10 and is rotated in a high speed to spread the resist liquid toward the outside in a diameter direction of wafer W by centrifugal force, thereby coating the resist liquid.
When the resist liquid is coated, it is necessary to coat the resist liquid on wafer W with high in-plane uniformity. Since most of the resist liquid on wafer W is thrown out of the wafer and wasted in the spin coating method, what is required is a method to reduce the amount of the resist liquid supplied onto wafer W.
As a method to save resist, so-called a pre-wet method is known in which a processing liquid to modify a surface of a substrate is coated on a surface of the wafer prior to coating a resist liquid such that the surface of the wafer becomes wet with a solvent thereby facilitating the spread of the resist liquid (see, e.g., Japanese Patent Application Laid-Open Nos. H07-320999 and 2007-299941). When the solvent is coated, a filter with a mesh body is disposed on a flow line from a processing liquid bottle to a solvent nozzle such that foreign matter in of the solvent is filtered in the filter.
Meanwhile, as circuit patterns are being miniaturized, the presence of the foreign matter with an infinitesimal size, which has not been practically a problem until now, is expected to affect the yield. For example, foreign matter (particles) may involve foreign matter derived from a crude liquid of the processing liquid, foreign matter derived from a transporting path which is mixed while the processing liquid is passing through an apparatus from a crude liquid tank, or ionized metal. Various designs have been executed to remove the foreign matter from the processing liquid. However, there is a limit in miniaturizing meshes of filters and it is difficult to remove an ion by an existing filter.